Embodiments of the present invention relate to a semiconductor device and a method for manufacturing the same.
A variety of power sources are available for operating a capacitor in a cell region and other elements in a peripheral region. Operation of the power sources produces noise. In order to reduce such noise, reservoir capacitors have been widely used. Such reservoir capacitors can be formed either in the cell region or in the peripheral region.
Generally, the reservoir capacitor uses a MOS-type capacitor comprising a gate and a source/drain. One reason why the MOS-type capacitor is used is that a gate oxide film has superior inner pressure characteristics with respect to a voltage applied thereto. However, with the increasing integration degree of semiconductor devices, the area of the MOS-type capacitor formed in the semiconductor device needs to be reduced.
Since capacitance of the MOS-type capacitor is reduced in proportion to such reduction in a size of the capacitor, it is difficult for a MOS-type capacitor to be used as a reservoir capacitor for a highly integrated device. That is, while the conventional MOS-type capacitor has superior inner pressure characteristics, it has low electrostatic capacitance when it is employed for a semiconductor device with a small unit cell size. Thus, a MOS-type capacitor is not desirable as a reservoir capacitor in a highly-integrated semiconductor device.